Last updated: June 24, 2025
In December, the average temperature in Thornton, United States hovers around -5°C (23°F), with extremes ranging from a chilly -27°C (-15°F) to a milder 14°C (57°F). Expect 113 mm (4.5 in) of precipitation distributed over 13 days, contributing to an average humidity of 81%. Be prepared for a mix of cold and damp conditions!
In December in Thornton, the average temperature is -5°C (23°F). Maximums can reach 14°C (57°F), while minimums can drop as low as -27°C (-15°F). Travelers should be prepared for a wide range of temperatures, from brisk winter chill to relatively mild days.
In Thornton in December, the precipitation amount is 113 mm (4.5 in) accumulated over 13 days.
In Thornton in December, humidity is 81%. With an average temperature of -5°C (23°F), this humidity feels like a biting chill that penetrates deep into your bones, making outdoor activities uncomfortable and travel a challenge.
In Thornton in December, the maximum UV index is 2, which corresponds to a low exposure category. With this level of UV radiation, the time to burn is approximately 45 minutes. To learn more about the hourly UV index in Thornton, you can visit Hourly UV Index in Thornton.
UV Risk Categories
Weather in Thornton varies notably across the year, with each month offering distinct climate conditions. This page compares December’s weather to other months in Thornton, focusing on differences in temperature, rainfall, humidity, and UV levels.
| Temperature | Precipitation | Humidity | UV | |
|---|---|---|---|---|
| January Weather | -8°C (18°F) | 85 mm (3.4 inches) | 86% | moderate |
| February Weather | -6°C (21°F) | 86 mm (3.4 inches) | 84% | moderate |
| March Weather | -2°C (28°F) | 75 mm (2.9 inches) | 82% | high |
| April Weather | 5°C (41°F) | 129 mm (5.1 inches) | 80% | very high |
| May Weather | 12°C (53°F) | 98 mm (3.9 inches) | 72% | very high |
| June Weather | 17°C (63°F) | 105 mm (4.1 inches) | 72% | very high |
| July Weather | 20°C (68°F) | 135 mm (5.3 inches) | 67% | very high |
| August Weather | 19°C (66°F) | 99 mm (3.9 inches) | 66% | very high |
| September Weather | 15°C (59°F) | 71 mm (2.8 inches) | 71% | high |
| October Weather | 8°C (47°F) | 143 mm (5.6 inches) | 78% | moderate |
| November Weather | 0°C (33°F) | 119 mm (4.7 inches) | 84% | moderate |
| December Weather | -5°C (23°F) | 113 mm (4.5 inches) | 81% | low |